package com.yupi.springbootinit.component;

import cn.hutool.core.util.StrUtil;
import cn.hutool.crypto.SecureUtil;
import cn.hutool.crypto.symmetric.AES;
import com.yupi.springbootinit.common.ErrorCode;
import com.yupi.springbootinit.config.FeatureTicketProperties;
import com.yupi.springbootinit.exception.BusinessException;
import com.yupi.springbootinit.model.dto.ticket.FeatureTicketPayload;
import com.yupi.springbootinit.utils.JsonUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

/**
 * Feature Ticket 认证组件
 * 负责 Ticket 的生成、加密、解密和校验
 *
 * @author ziin
 */
@Component
public class FeatureAuthComponent {

    private static final Logger log = LoggerFactory.getLogger(FeatureAuthComponent.class);

    @Resource
    private FeatureTicketProperties ticketProperties;

    private AES aes;

    @PostConstruct
    public void init() {
        // 使用配置的 AES 密钥初始化加密器
        byte[] keyBytes = ticketProperties.getAesKey().getBytes(StandardCharsets.UTF_8);
        // 确保密钥长度为 16 字节（AES-128）
        if (keyBytes.length < 16) {
            byte[] paddedKey = new byte[16];
            System.arraycopy(keyBytes, 0, paddedKey, 0, keyBytes.length);
            keyBytes = paddedKey;
        } else if (keyBytes.length > 16 && keyBytes.length < 24) {
            byte[] truncatedKey = new byte[16];
            System.arraycopy(keyBytes, 0, truncatedKey, 0, 16);
            keyBytes = truncatedKey;
        } else if (keyBytes.length > 24 && keyBytes.length < 32) {
            byte[] truncatedKey = new byte[24];
            System.arraycopy(keyBytes, 0, truncatedKey, 0, 24);
            keyBytes = truncatedKey;
        } else if (keyBytes.length > 32) {
            byte[] truncatedKey = new byte[32];
            System.arraycopy(keyBytes, 0, truncatedKey, 0, 32);
            keyBytes = truncatedKey;
        }
        this.aes = SecureUtil.aes(keyBytes);
        log.info("FeatureAuthComponent 初始化完成，AES 密钥长度: {} 字节", keyBytes.length);
    }

    /**
     * 生成 Feature Ticket
     *
     * @param tenantId      租户 ID
     * @param userId        用户 ID
     * @param machineId     设备 ID
     * @param featureCode   功能代码
     * @param expireSeconds 有效期（秒）
     * @return 加密后的 Base64 字符串
     */
    public String generateTicket(Long tenantId, Long userId, String machineId,
                                  String featureCode, Long expireSeconds) {
        if (tenantId == null || userId == null || StrUtil.isBlank(machineId) || StrUtil.isBlank(featureCode)) {
            throw new BusinessException(ErrorCode.PARAMS_ERROR, "生成 Ticket 参数不完整");
        }

        // 计算过期时间
        long expireTime = expireSeconds != null ? expireSeconds : ticketProperties.getDefaultExpireSeconds();
        long expiryTimestamp = System.currentTimeMillis() + (expireTime * 1000);

        // 构建载荷
        FeatureTicketPayload payload = FeatureTicketPayload.builder()
                .tenantId(tenantId)
                .userId(userId)
                .machineId(machineId)
                .featureCode(featureCode)
                .expiryTimestamp(expiryTimestamp)
                .build();

        // 序列化为 JSON
        String jsonPayload = JsonUtils.toJsonString(payload);

        // AES 加密
        byte[] encryptedBytes = aes.encrypt(jsonPayload.getBytes(StandardCharsets.UTF_8));

        // Base64 编码（URL 安全）
        return Base64.getUrlEncoder().withoutPadding().encodeToString(encryptedBytes);
    }

    /**
     * 解密 Ticket
     *
     * @param encryptedTicket 加密的 Ticket 字符串
     * @return 解密后的载荷
     */
    public FeatureTicketPayload decryptTicket(String encryptedTicket) {
        if (StrUtil.isBlank(encryptedTicket)) {
            throw new BusinessException(ErrorCode.TICKET_INVALID, "Ticket 不能为空");
        }

        try {
            // Base64 解码
            byte[] encryptedBytes = Base64.getUrlDecoder().decode(encryptedTicket);

            // AES 解密
            byte[] decryptedBytes = aes.decrypt(encryptedBytes);
            String jsonPayload = new String(decryptedBytes, StandardCharsets.UTF_8);

            // 反序列化
            return JsonUtils.parseObject(jsonPayload, FeatureTicketPayload.class);
        } catch (Exception e) {
            log.error("Ticket 解密失败: {}", e.getMessage());
            throw new BusinessException(ErrorCode.TICKET_INVALID, "Ticket 无效或已损坏");
        }
    }

    /**
     * 校验 Ticket
     *
     * @param encryptedTicket   加密的 Ticket
     * @param requestMachineId  请求中的设备 ID
     * @param requiredFeatureCode 需要的功能代码（可选，为 null 时不校验）
     * @return 校验通过的载荷
     */
    public FeatureTicketPayload validateTicket(String encryptedTicket, String requestMachineId,
                                                String requiredFeatureCode) {
        // 解密 Ticket
        FeatureTicketPayload payload = decryptTicket(encryptedTicket);

        // 校验过期时间
        if (payload.getExpiryTimestamp() == null || System.currentTimeMillis() > payload.getExpiryTimestamp()) {
            throw new BusinessException(ErrorCode.TICKET_EXPIRED, "Ticket 已过期");
        }

        // 校验设备 ID
        if (StrUtil.isBlank(requestMachineId)) {
            throw new BusinessException(ErrorCode.PARAMS_ERROR, "请求中缺少设备 ID");
        }
        if (!requestMachineId.equals(payload.getMachineId())) {
            log.warn("设备 ID 不匹配，请求: {}, Ticket: {}", requestMachineId, payload.getMachineId());
            throw new BusinessException(ErrorCode.TICKET_MACHINE_MISMATCH, "设备 ID 不匹配");
        }

        // 校验功能代码（如果指定）
        if (StrUtil.isNotBlank(requiredFeatureCode) && !requiredFeatureCode.equals(payload.getFeatureCode())) {
            log.warn("功能代码不匹配，需要: {}, Ticket: {}", requiredFeatureCode, payload.getFeatureCode());
            throw new BusinessException(ErrorCode.TICKET_FEATURE_MISMATCH, "功能代码不匹配");
        }

        return payload;
    }

    /**
     * 简化校验（仅校验有效性和设备 ID）
     *
     * @param encryptedTicket  加密的 Ticket
     * @param requestMachineId 请求中的设备 ID
     * @return 校验通过的载荷
     */
    public FeatureTicketPayload validateTicket(String encryptedTicket, String requestMachineId) {
        return validateTicket(encryptedTicket, requestMachineId, null);
    }
}